NAME

GIS::Distance::Formula::Cosine - Cosine distance calculations.

DESCRIPTION

Although this formula is mathematically exact, it is unreliable for small distances because the inverse cosine is ill-conditioned.

Normally this module is not used directly. Instead GIS::Distance is used which in turn interfaces with the various formula classes.

  a = sin(lat1) * sin(lat2)
  b = cos(lat1) * cos(lat2) * cos(lon2 - lon1)
  c = arccos(a + b)
  d = R * c

This method is called by GIS::Distance's distance() method.

Aran Clary Deltac <bluefeet@cpan.org>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.